ATLANTA -- Republican presidential candidate Herman Cain is vowing to "set the record straight" at a news conference one day after a fourth woman -- and the first to reveal her identity -- accused him of inappropriate sexual behavior a decade ago, the latest in a string of claims that have rocked his presidential campaign.

"There is not an ounce of truth to all these allegations" and the graphic account from Sharon Bialek is "totally fabricated," the Georgia businessman told late-night talk show host Jimmy Kimmel.

Bialek stood by her accusation when asked about it Tuesday morning in the wake of Cain's denial, saying in a nationally broadcast interview that she had "nothing to gain" by coming forward. She said,"It's not about me. I'm not running for president."

Cain planned to address the latest furor in more detail Tuesday afternoon in Phoenix as he seeks to stem the fallout of a controversy stretching into its second week.

"I'm going to talk about it," Cain said, adding "we are taking this head on" -- a reversal from just days ago when told reporters he was done answering questions about the matter.

That was before Bialek went on national television Monday and provided a name and a face to what had, until then, been at least three anonymous sexual harassment allegations against Cain. Bialek's accusations -- that Cain groped her in a car after she asked for his help finding a job -- spun his unorthodox campaign into an uncertain new territory.

An upstart in the presidential race, Cain shot to the top of public opinion polls and emerged, however temporarily, in surveys as the main conservative challenger to Mitt Romney. Tea party activists and conservatives unenthused with the former Massachusetts governor have flocked to Cain's tell-it-like-it-is style and self-styled outsider image in recent weeks.

There were, however, growing signs of unease in conservative circles as, one by one, a handful of women claimed Cain acted inappropriately toward them while the head of the National Restaurant Association in the 1990s.

"He deserves a fair chance. But that doesn't mean he gets a pass. These are not anonymous allegations anymore unfortunately," said New Hampshire conservative activist Jennifer Horn, who last week had condemned media coverage of the allegations against Cain. "He does need to take another step and answer a few more questions."

"Oh," exclaimed South Carolina GOP Chairman Chad Connelly said when told details from Bialek's news conference. He said character issues matter in a state where the last governor tearfully confessed an affair and the current governor faced unproven allegations from two men that she had affairs. "Our voters care about moral attitude," Connelly said. "Character does matter."

Still, Cain backers remained solidly behind the former pizza company executive. They pointed to the presence of Gloria Allred -- a high-profile attorney with Democratic ties -- alongside Bialek at a news conference on Monday in New York as proof that the latest claim was a partisan smear.

"The fact that she's involved removes all credibility," Georgia Christian Coalition president Jerry Luquire said. "If he says he didn't do anything than I believe him."

Bialek said Tuesday she had no financial motivation to come forward, wasn't offered a job and wasn't being asked by Allred to pay a legal fee.

"I'm just doing this because it's the right thing to do," she said in one interview. Bialek said she waited so long to come forward because "I was embarrassed ... and I just kind of wanted it to go away."

Asked about Cain's characterization of her charges as a "total fabrication," Bialeck stood her ground. "I wanted to give him a platform to come clean, to tell the truth," she said. "I was trying to be nice about it and it just didn't work."

Bialek is the fourth woman to say that Cain engaged in inappropriate behavior during his time at the helm of the restaurant group.

At least two women who worked there at the time filed sexual harassment complaints.

A third woman told The Associated Press last week that she considered filing a workplace complaint against Cain over what she deemed sexually suggestive remarks and gestures that included a private invitation to his corporate apartment. And a former pollster for the restaurant association has said he witnessed yet another episode involving a different woman.

In New York on Monday, Bialek said Cain -- an acquaintance -- made a sexual advance in mid-July 1997, when she had travelled to Washington to have dinner with him in hopes he could help her find work or get her job back at the National Restaurant Association after she had been fired from a job in the group's education arm.

The two met in Washington, she said, and after having dinner were in a car for what she thought was a ride to an office building.

"Instead of going into the offices he suddenly reached over and he put his hand on my leg, under my skirt toward my genitals," she said. "He also pushed my head toward his crotch."

She said she asked Cain what he was doing and recalled he replied, "You said you want a job, right?"

None of Cain's other accusers has provided details as graphic as Bialek's account. But Joel Bennett, an attorney who represents one of them, said her details were "similar in nature" to what his client encountered.

In his only public appearance of the day, Cain told Kimmel during the late-night interview that he got angry and disgusted as he watched Bialek and Allred. He said his wife didn't watch it but that he called her immediately afterward.

"Mr. Cain has never harassed anyone," spokesman J.D. Gordon said in a statement. Aides insisted that the newest allegation changed nothing and said Cain would move forward with his plans to attend a private speech in Phoenix on Tuesday morning and a debate Wednesday night in Michigan.

"We are staying on message and talking about the issues," Gordon told The Associated Press.

As if to prove the point, the Cain campaign released a new web video -- targeting voters in the lead-off caucus state of Iowa -- highlighting what it says are excessive federal regulations on farmers that are driving up costs for consumers.

But, behind the scenes, the campaign appeared to hunker down in damage-control mode; voicemails for Gordon and campaign manager Mark Block were full by mid-afternoon.

Later that night, the campaign announced that Cain would appear at the Phoenix news conference.

Aides made clear that he would fight the allegations, casting the allegations as baseless and seeking to undermine the credibility of both Bialek and her attorney in the news release.

"The questions the media should be asking are who's paying for Gloria Allred's fee, how did Ms. Bialek get introduced to Ms. Allred, and was she paid to come forward with these false accusations or was she promised employment?" the news release said.Allred has said Bialek approached her and that her client didn't get compensated for stepping forward.

Bialek appeared in interviews Tuesday on ABC's "Good Morning America," CBS' "The Early Show," and NBC's "Today" show and CNN.